EP2246221B1 - Go-kart with elastic shock absorbing means, corresponding device - Google Patents

Description

1. Field of the invention

The field of the invention is that of the absorption of kinetic energy in the event of impact, in particular on a recreational vehicle, and in particular a go-kart. In other words, the invention relates to shock absorbing means, or shock absorbers, and, in particular, karts equipped with such shock absorbers.

More generally, the invention solving this problem, discussed later, can find applications in many areas where it is necessary or desirable to absorb, relatively repeatedly, shocks or relatively large forces, without destruction or deterioration. Thus, for example, the invention can be applied to any vehicle, and even to any fixed object whose integrity must be protected in the event of impact by a vehicle or any other moving object.

2. Prior Art

The primary function of a shock absorber, in the field of the automobile as in that of the kart, is the safety of the driver.

Despite these similarities, there are major differences between the car and the kart.

In the case of the automobile, the energy absorption must ensure the safety of the driver in high speed shocks (example 65 km / h). Given the energies involved and the dimensions of the vehicles, this can only be achieved by an irreversible deformation of the front part of the vehicle (plastic deformation).

• l'exploitation du matériel dans un contexte de location fait que le système d'absorption doit être à déformation réversible, afin d'éviter des opérations de maintenance trop fréquentes et trop coûteuses,
• la distance entre les pieds du pilote et la face avant du kart est limitée (typiquement 15 à 25 cm), ce qui restreint l'espace disponible pour intégrer un absorbeur d'énergie,
• les cas de chocs sont multiples, en direction et en intensité.

In the case of the kart, the stresses are different, in particular because a second function of the absorber, specific to the kart, is to protect the chassis by reducing the forces to which it is subjected, and thus increase the duration of life. So :

• the exploitation of the equipment in a rental context means that the absorption system must be reversibly deformed in order to to avoid frequent and costly maintenance operations,
• the distance between the pilot's feet and the front of the kart is limited (typically 15 to 25 cm), which limits the space available to integrate an energy absorber,
• the cases of shocks are multiple, in direction and intensity.

• absorber un maximum d'énergie dans un espace donné,
• dimensionner l'absorbeur pour ne pas dépasser un nombre limite imposé de g (exemple 10 g), pour une énergie cinétique de référence donnée (exemple énergie d'un kart allant à 10 km/h et de masse 200 kg),
• absorber cette énergie de façon réversible, c'est-à-dire en s'interdisant l'utilisation d'énergie de déformation plastique, et sans phénomène de vieillissement après un nombre élevé de cycles,
• conserver un niveau élevé d'absorption, pour des angles de chocs ou des excentrations variés.

As a result, the technical nature of the problem to be solved is as follows:

• absorb a maximum of energy in a given space,
• dimension the absorber so as not to exceed an imposed limit of g (for example 10 g), for a given reference kinetic energy (example energy of a go-kart going to 10 km / h and mass 200 kg),
• to absorb this energy reversibly, that is to say by prohibiting the use of plastic deformation energy, and without aging phenomenon after a high number of cycles,
• maintain a high level of absorption, for different angles of impact or eccentricity.

• ne pas dépasser une accélération supérieure à 10 g au cours du choc,
• ne pas présenter de déformation permanente du châssis après l'essai,
• pouvoir satisfaire ces exigences pendant 10 tests consécutifs.

For example, the technical and safety rules of karting (in France), provide that the damping system of some karts must meet the following requirements for a mass kart M = 200 kg launched at a speed V = 10 km / h against a wall:

• do not exceed an acceleration greater than 10 g during the shock,
• do not show any permanent deformation of the chassis after the test,
• ability to meet these requirements for 10 consecutive tests.

In this example, we therefore find that we define a reference energy of the kart (1/2 * M * V ² ), and that we try to limit the number of g when this kart hits a wall with this energy reference.

The solutions proposed in the automobile do not answer the problem posed by the kart, because they are based on the plastic deformation energy, which is not acceptable for karts.

The solutions used in the kart, such as silentblocs or that described in the patent EP-1 805 063 , do not completely answer the problem.

The silentblocs, which are generally of small size, have the disadvantage of having a limited compression ratio, of being very hard beyond this level and therefore do not allow to obtain a deformation energy. raised in a small space, while limiting the number of g. Their resistance to aging is limited, especially when subjected to combined stresses (compression plus shear), which is the case in karts.

The solution described in the patent EP-1 805 063 proposes that the kart be equipped with a shock shield, protecting at least the front, and a set of protection protecting at least the rear and the wheels, which must not be embedded in another kart, in order to in particular to avoid the risk of rollover. It allows to obtain, in a small space, a high deformation energy while limiting the number of g.

On the other hand, it has at least three disadvantages: the first is that of having an aging effect after a high number of cycles; the second is, beyond the reference energy, to present plastic deformations; the third is that, in the event of an impact with an energy higher than the reference energy, the absorption system becomes hard and generates high forces or accelerations which can cause irreversible damage to the chassis.

In other words, this system does not have enough "reserve" beyond the reference shock for which it is intended.

In actual use, these energy shocks greater than the reference energy exist. It is therefore desirable that the absorption device optimizes the amount of absorbable energy in the available space so as not to arrive at a "hard point", except in the case of very exceptional shocks.

This problem of optimization of the deformation energy for a given available space is illustrated by the three curves of the figure 4 , corresponding to the shock of the previous example (mass 200 kg, 10 km / h).

In the figure 4 the maximum force corresponds to 10 g on a 200 kg go-kart, ie 20 000 N.

The deformation energy is, in each case, the area under the displacement-force curve.

Curve C1 represents a linear and theoretical behavior of an absorber.

Curve C2 corresponds to one embodiment of the invention, and is commented thereafter.

The curve C3 represents a nonlinear behavior whose deformation energy, with equal displacement, is lower than that of the linear absorber. This absorber uses a larger deformation than the linear absorber to absorb the reference energy. It corresponds to an absorber according to the technique of the patent document EP-1 805 063 .

The behavior of the absorber, in the case of shocks that go beyond the reference energy (corresponding to 10 km / h and 200 kg) is also important, because such shocks exist in the reality of exploitation karts. The importance of this behavior is also illustrated by the figure 4 .

The absorber corresponding to the linear curve C1, is such that, beyond a certain depression, it behaves in hard point: the force increases very strongly for a small displacement. This means that any additional energy to be absorbed beyond the reference energy results in high forces on the chassis and the driver.

The absorber of curve C3 has a similar behavior.

Finally, the manufacturing cost and the maintenance cost of the protection device must be as low as possible. It is therefore a question of limiting number of items needed and their size, and their mounting on the vehicle should be easy. In addition, it is desirable that these elements can be mounted in places in which they do not interfere with the vehicle components.

Various techniques are known in the field of motor vehicles, and in particular an approach described for example in the documents US 5,570,918 . US 4,300,38 , or DE 195 42 346 , implementing a fixed element relative to the chassis of the vehicle, carrying and guiding an energy absorbing element. This approach can not adapt directly to the karts and would not be effective, especially in the presence of lateral shocks on the front protection element.

3. Objectives of the invention

The object of the invention is in particular to overcome at least some of these disadvantages.

The above discussion shows that there is therefore a problem of tolerance of successive shocks, without destruction of parts and without degradation of the reaction characteristics of the absorber device. Furthermore, for the same efficiency, it is desirable to limit the footprint at rest of the absorber device, in order to limit the grip on the vehicle that carries it.

In particular, an object of the invention is, according to at least one embodiment, to provide a kart capable of tolerating a large number of successive shocks, without plastic deformation. For example, in at least one particular embodiment, the invention aims to effectively meet the requirements of successive crash tests mentioned above.

Another object of the invention is, according to at least one embodiment, to provide a kart whose shock absorption is effective, without the bulk of the protection, and more generally the front part, is too important, and / or that the stroke of the damping means is too important.

In other words, according to at least one embodiment, an object of the invention is to provide a go-kart capable of absorbing a lot of energy with little travel (to reduce congestion) and little constraint; ie a small number of G, so a weak force.

Another goal is to optimize the amount of energy that can be absorbed in the available space.

Yet another object of the invention is, according to at least one embodiment, to provide such a kart whose efficiency and dynamic qualities are not deteriorated by the damping means.

The invention also aims, according to at least one embodiment, to provide such a kart, the manufacture of which remains sufficiently simple, without the need for complex or expensive parts or tools, and whose maintenance is easy.

4. Summary of the invention

For this purpose, the invention relates first of all to a kart according to claim 1.

Thus, the absorption means integrate, on the one hand, the desired elastic material, but which, alone, would only imperfectly act as an absorber, for at least two reasons. The first is that the critical compressive load corresponding to the first mode of buckling of the elastic material would be too low, thus preventing to use a significant part of the race available to absorb energy. The second is that the elastic material alone would be too sensitive to any eccentricity of the compression force, thus causing premature buckling and therefore the same disadvantages as a first mode of buckling too low.

The absorption means integrate, on the other hand, at least one buckling control element. This allows to prevent or limit the (or) first mode (s) of buckling of the elastic material, and also to reduce the decline in the critical load due to possible eccentric forces applied.

The term "buckling" refers to the buckling instability deformation of the elastic absorbent member, in particular, its beam buckling modes. For example, if the elastic material is of hollow cylindrical shape, it may be to eliminate the beam buckling modes to work the wall buckling modes.

The term "controlled" means that certain modes of buckling are eliminated or limited.

• une phase de compression dudit élément absorbant élastique ;
• une phase de compression en flambage contrôlé, dans laquelle l'élément de contrôle de flambage contraint l'élément absorbant élastique de façon à s'opposer à son flambage. Par exemple, l'élément élastique peut être contraint à travailler selon un ou des modes de flambement qui permettent d'obtenir une courbe force / déplacement souhaitée.

Thus, the buckling control element can act, according to a preferred embodiment, on the corresponding absorbent element so as to successively allow, during an impact:

• a compression phase of said elastic absorbent element;
• a controlled buckling compression phase, in which the buckling control element constrains the elastic absorbent element so as to oppose its buckling. For example, the elastic element may be forced to work according to one or more buckling modes which make it possible to obtain a desired force / displacement curve.

The axis defined by the buckling control element is pivotally movable, so as to orient and follow the movement, and tend to align parallel to the axis the impact of a shock (or at all the least to get closer to it), when it is oblique, that is to say applied laterally on the protective element.

Thus, the device of the invention allows effective absorption of the shock, whether it is frontal or oblique.

At least one of the buckling control elements is advantageously provided with an anti-dislocation device.

The buckling control member may be mounted to the frame so as to be pivotable in a predetermined angular range against the angular restoring force of resilient means to a rest state orientation.

According to a particular embodiment, at least one control element may also be provided, at its end, with an elastic connecting element or with a ball joint, in order to limit the stresses on the control element, during oblique shocks.

This limits the risk of tearing the link, and ensures the orientation of the buckling control element.

Advantageously, the elastic absorbent element is hollow and the buckling control element extends inside the elastic absorbent element.

Congestion is reduced, and easy assembly.

In such a case, at least one of the elastic absorbent element and the buckling control element may be cylindrical.

The component of the resistance forces of the sectors of the section of the elastic absorbent element is thus centered on the cylinder axis, which limits the risk of buckling, that is to say of geometric breakage as indicated above. .

Preferably, the absorption means comprise two resilient absorbent elements extending parallel to a longitudinal axis of the frame.

In an interesting embodiment, the frame carries a first blade adapted to cooperate with a second blade associated with the protection element, the resilient absorbent element being mounted between the first and second blades.

At least one of the blades can be elastic, thus contributing to absorb the total deformation energy.

The first and second blades may have end sections mutually coupled by a recessed connection or a slide connection.

The invention also relates to a kinetic energy absorption device according to claim 11.

It will have been understood that the absorber device, or absorption means, according to the invention can be disposed anywhere of a vehicle, or even, twice, anywhere in a fixed object likely to be struck. .

Advantageously, the elastic absorbent element is hollow and the buckling control element extends inside the elastic absorbent element.

Finally, the invention relates to a use of an energy absorbing device according to the invention, between two said pieces constituted respectively by a frame and a protection element mounted on the frame, to absorb the energy induced by a contact. on the protection element.

5. List of figures

• la figure 1 est un schéma, en vue de dessus, de la partie avant d'un châssis de kart équipé du dispositif ci-dessus, à l'état de repos,
• la figure 2 est homologue de la figure 1, mais pour un état de compression du dispositif d'absorption d'énergie, lors d'un choc,
• la figure 3 est une vue éclatée en perspective d'éléments absorbeurs, à propriétés élastiques, du dispositif d'absorption d'énergie, et
• la figure 4 illustre des courbes de réponse de force de résistance en fonction de la longueur d'enfoncement de divers types de dispositifs absorbeurs ;
• la figure 5 illustre des courbes de réponse de force de résistance en fonction de la longueur d'enfoncement du dispositif, pour une série de chocs successifs.

The invention will be better understood with the aid of the following description of an embodiment of a go-kart chassis equipped with an elastic shock energy absorption device according to the invention, the operation and operation of which are described in FIG. use will be explained, all with reference to the appended drawing, in which:

• the figure 1 is a diagram, in plan view, of the front part of a go-kart chassis equipped with the above device, in the idle state,
• the figure 2 is counterpart of the figure 1 , but for a state of compression of the energy absorption device, during an impact,
• the figure 3 is an exploded perspective view of absorber elements, with elastic properties, of the energy absorbing device, and
• the figure 4 illustrates resistance force response curves as a function of the sink length of various types of absorber devices;
• the figure 5 illustrates resistance force response curves as a function of the driving length of the device, for a series of successive shocks.

6. Description of an embodiment of the invention and variants

The Figures 1 and 2 are top views of the front of a kart frame 1 equipped with a device 11 for absorbing kinetic shock energy (or damping device, or absorber device), whose figure 3 is an exploded perspective view of the constituent elements, according to a particular embodiment of the invention.

In this example of implementation, the absorber device 11 is therefore located in the front position of the chassis 1 to cooperate with a front blade 13 for protecting the kart undergoing the impact of an external object and thus retreating towards the chassis 1, by rising vertical direction on the Figures 1 and 2 , where the reference 10 designates a longitudinal median axis of the frame 1, or on one of the sides of this blade (side impact, or oblique).

The invention is indeed suitable for the absorption of frontal or oblique shocks. This is possible because the buckling control elements, or buckling, are rotatable, or pivotable, over a predetermined angular range, so as to tend to align with the axis of impact.

For ease of presentation, the kart is supposed to rest on a horizontal ground, that is to say that the axis 10 is horizontal. The so-called transverse direction is defined relative to the chassis 1, unless otherwise indicated, that is to say that it is the horizontal direction on the Figures 1 and 2 .

The chassis 1 comprises, in the front part, a transverse support structure 2 composed of two pipes, one of which, lower, is fixed to the rest of the frame 1 by two short longitudinal longitudinal spacers 5 mutually spaced laterally and the second, upper, is fixed directly on the chassis 1 by two "ears". The transverse support structure 2 comprises, between the upper and lower pipes, a passage 4, longitudinal with respect to the frame 1 and therefore transverse to the transverse carrier structure 2, allowing the passage of two axes, or longitudinal bodies, 26 of two respective guide members 25, exposed later.

The front face of the structure 2 carries a blade 3 of elastic material, here polyethylene whose lateral edge, visible on the Figures 1 and 2 , generally has a concavity-shaped profile concavity facing forward, with however first and second end sections 31, 32 extending somewhat backwards, after a respective bend 33, 34 with open concavity to the rear. The overall profile of the blade 3 is thus W, with short lateral branches.

A protective element is mounted at the front of the kart. It comprises in particular a spoiler, or cover, 12 (not shown integrally) and a front blade 13. The cover 12 has a function of cover of the technical part and / or dressing and decoration. It may consist of a protective plastic covering shell, partially drawn, interposed between a transverse bar 21 and the front blade 13. This is made of elastic material, here polyethylene. Its lateral edge, visible on the Figures 1 and 2 , generally has a concave profile profile concavity turned rearward.

The front protection blade of the kart 13 and the blade 3 are intended to support the absorber materials and, by their deformations, to allow the work, and partially contribute to absorbing the deformation energy of the assembly.

The blades 13 and 3 are recessed relative to each other by the end sections 31, 32 and 131, 132. It is conceivable that they slide relative to each other, but the solution here proposed is based on the deformations of the blades.

It should be noted that the use of a slide as described in the document EP-1805063 is possible. It is also possible to combine the two systems by integrating a slide on the controlled buckling absorption solution as on the solution of the document EP-1805063 . That would have to have rigid wheel revolutions sliding relative to the chassis 1 this would better protect the wheels and increase the vertical stability of the system.

The volume delimited by the blades 3 and 13 contains the absorber device 11, in duplicate in this example. The two absorber devices 11, arranged symmetrically with respect to the axis 10, are intended to absorb the impact energy, by a deformation essentially, and preferably purely elastic, and not of the plastic type, in order to avoid an effect memory to preserve, even after several shocks, the original performance.

To do this, a rear face of the front blade 13 carries the transverse bar 21, clearly visible on the figure 3 , whose rear faces of two end sections carry two front ends of two respective blocks of resilient cushioning material in the form of columns 23 extending longitudinally and having a planned direction of longitudinal compression, that is to say, parallel to the axis 10, which here represents the direction of the shock.

In this example, the columns 23 are cylindrical and tubular, each having an axial passage housing an axial guide rod, here constituted by a guide body 26, belonging to a guide member 25. An end flare 27 of each column ensures an anti-disengagement function of the device during a lateral or rear impact.

An elastic block 22, also called silent block, or alternatively a ball joint, a cable or any other connection to limit the bending stresses on this element, serves to separate the guide bodies 26 vis-à-vis the transverse bar 21 , especially to avoid tearing in case of oblique impact. Thus, the guide bodies (which are, in this embodiment, cylindrical rods) 26 tend to align parallel to the axis of the impact (or at least to approach it), that the either frontal or oblique. The elastic block 22 acts on the guide body 26 and helps it to take this direction.

The guide bodies may in particular be made of plastic.

The elastic block 22 is fixed by screw on the rear surface considered of the end section of the bar 21, to receive a front free end section of the guide body 26, to give it a certain degree of play, to avoid any risk of tearing. The rear end of each column 23 is covered with a cylindrical protective cap 24, pierced with an axial hole through which the guide body 26 passes.

The columns 23 are made for example of polyurethane, or any other material having the required qualities of elasticity and compression.

The length of the guiding body 26 remaining free corresponds substantially to the column length 23. It can however be provided a surplus (for example adjustable by screwing), so that the columns 23 are initially preloaded under a certain axial compression force, so to provide increased initial resistance against compressive forces in the event of impact.

The figure 2 shows that, after an intense frontal impact, the columns 23 are strongly axially crushed, that is to say that the cylindrical form of rest has deformed, ideally in this example, into a generally ring annular form. The constituent material was indeed deformed radially by buckling effect. The guide bodies 26 have slid longitudinally in the passage 4 formed between the tubes of the transverse structure 2. Of course, the rear blade 3 has two recoil passages of the body 26, or it is shaped to circumvent the space passing the bodies 26 of the guide elements 25, by a deviated shape above or below, in front view. Indeed, in general, all the free sections of the blades 3 and 13, that is to say those which serve only as a bending element, without support on another element, are not necessarily in the same slice of horizontal space. Similarly, the end sections 31, 131 and 32, 132 may be at a level other than that of the columns 23.

The figure 2 shows that the guide elements 25 have preserved the axial symmetry of each column 23, that is to say that its front end portion has remained longitudinally "opposite" the rear end section. The stretch front end has thus moved in a path only along the geometric axis of the column 23, without lateral deviation relative to this local axis, except possibly an initial radial clearance existing around the guide body 26. However, note that the material of the column 23, compressed axially, tends to flame radially externally but also internally, that is to say, it tends to approach the guide body 26 and thus to cancel any initial radial clearance. There is thus a self-centering.

The figure 2 is intended to illustrate only the change of shape of the columns 23, that is to say that the influence of the deformation of the front blade 13 on the rear blade 3 has not been shown, the rear blade 3 is drawn in its form of rest.

In fact, the two blades 3 and 13 being mutually clamped by the first and second end portions 31, 131 and 32, 132, that is to say with the same direction of instantaneous local extension, without the possibility of sliding, the rear blade 3, W profile, will recover, under the effect of two types of constraints.

On the one hand, the depression of the central part of the front blade 13, at the beginning of the shock, causes pivoting of the end sections 131, 132 forwards, that is to say toward a direction d more transversal extension. The end sections 31, 32 of the rear blade 3 are thus brought back in this same transverse direction, against the bending resistance force of the associated elbow 33, 34, whose angle, here about 100 degrees at rest, will open.

On the other hand, the increasing transverse grip of the front blade 13 tends to separate the rear blade 3. This spacing, in the transverse direction, and the longitudinal recoil thrust of the front blade 13, thus cause a deformation of the rear blade 3, and precisely a decrease in its curvature. Its transverse grip can thus follow the increase in the transverse grip of the front blade 13.

Note that the guide elements, whatever their embodiment (body 26 or other), can be fixed by their front end (block 22 as drawn) or backward if the crushing stroke of the front blade 13 allows it. The guide element is then fixed relative to the frame 1. The passage 4 located in the rear blade 3 and the structure 2 is useful in the case where the guide member 25 is fixed on the front. There is no passage in the blade before 13, because this blade serves as contact face in case of shock.

It can also be expected that the guide elements are not fixed, but only maintained at the desired level. For example, if their sliding is necessary, the passage 4 allows the retraction of the guide element 25 in a sufficient space located behind the transverse structure 2.

In particular, in the illustrated embodiment, the two guide elements 25 define, in plan view, two longitudinal sides of a parallelogram whose two transverse sides are constituted by, in front, the bar 21 and, behind, a virtual line connecting the two passages 4, or an equivalent, defining the sliding rear position of the guide bodies 26. This parallelogram, of rectangular shape when the assembly is free of any lateral constraint, may deform, in case side impact, because each of its four corners is an assembly allowing a pivot between the two sides then considered.

Indeed, the two front corners comprise the respective elastic blocks 22, which have a function of a ball joint, their elasticity ensuring, at rest, maintaining 90 degrees each of these two front corners. As the screwing of the guide bodies 26 puts in slight axial compression the columns 23 through which they pass, the rear end thereof bears against a purely transverse front surface of the frame 1, specifically the cap 24, so that it is the columns 23 which elastically impose, to the respective guiding bodies 26, a perfectly longitudinal direction.

It will be noted that the elastic blocks 22 of the front corners can be replaced by ball joints, or equivalent, free of angular return elasticity, since, at rest, the columns 23 are already maintained in purely longitudinal alignment, by their rear end. These ball joints or equivalent elements can be reduced to simple coupling elements preventing the dissociation of the two considered sides of the rectangle, that is to say without necessarily ensuring mutual rotation guidance thereof.

The two rear corners are defined by the passages 4, which form a kind of collars which determine the position (longitudinal x, transverse y, and height z) of passage back relative to the frame 1, that is to say inhibit three degrees of freedom in translation respectively according to three orthonormal axes X, Y, Z. However, the passages 4 or equivalent allow at least one degree of freedom in pivoting, this in the horizontal plane defined by the axes X, Y, c ' that is, around a local vertical axis.

Lateral impact on the element 11 will not cause disassembly of the guide elements 25 but, decentering the bar 21 relative to the longitudinal axis 10, it will only transform the rectangle above into a parallelogram whose two longitudinal sides (that is to say the guide elements 25) will be inclined on the longitudinal axis 10. The assembly thus remains functional to ensure the desired damping by recoil of the two guide elements 25. It is conceivable that it may be useful to also provide a second degree of freedom in pivoting in a vertical longitudinal plane if the shock may have a vertical component.

To allow the pivoting above, each passage 4 has a very limited axial length, associated with a passage template slightly larger than a template of transverse size of the guide body 26 which passes through it. Specifically, the passage 4 has, in horizontal axial section, a rectangular shape (of which a first transverse distance, of passage, between two opposite longitudinal sides corresponds to the passage template) which freely houses a rectangle, therefore narrower, (of which a second transverse distance, of space, between two opposite longitudinal sides corresponds to the clearance jig) representing the relevant section of the guide body 26. The guide body 26 can thus pivot about the local vertical axis, in an angular range of greater than (a) the axial length of passage 4 is reduced (no precise longitudinal guidance), and that b) the first and second transverse distances have a high value difference.

For example, it can be provided that the limits of the above angular range each extend to 15 or even 30 degrees respectively on either side of the direction of the longitudinal axis 10. In such a range, the sliding guide bodies 26 in the respective passages 4 remain assured since, although the impact is somewhat transverse, the corresponding force has a predominant axial component and there is no hard friction seizing on the walls of the passages 4, the two respective templates remaining compatible.

It is conceivable that the principle of deformation of the parallelogram explained above is applicable whatever the number of guide elements 25, the parallelogram thus being reduced to an "I" if there is only one element of guidance 25.

The beam of curves of the figure 4 represents a response curve C2 of the absorber device 11 according to one embodiment of the invention, compared with the curves C1 and C3 commented in the preamble, showing the correspondence between the crushing force of the shock and the recoil stroke, or crushing columns 23, necessary to generate elastic reaction forces opposing the force of the impact.

It will be understood that this curve C2 has the advantage of having a large absorption capacity, beyond the reference energy: the force increases, but gradually, with a first rising portion 41, a second section 42 in a slightly descending false flat, and a third rising section 43, with a slope similar to that of the first section. The forces to which the conductor and the frame are subjected for energies beyond the reference energy are substantially lower than those of the other two absorbers.

• une phase (41) de compression de l'élément absorbant élastique ;
• une phase (42) de compression en flambage contrôlé, dans laquelle l'élément de contrôle du flambage (26) contraint l'élément absorbant élastique (23) de façon à s'opposer à son flambage ;
• éventuellement, une nouvelle phase (43) de compression de l'élément absorbant élastique.

We can note, on curve C2, the following three successive phases:

• a compression phase (41) of the resilient absorbent element;
• a controlled buckling compression phase (42), wherein the buckling control member (26) constrains the resilient absorbent member (23) to oppose buckling thereof;
• optionally, a new phase (43) of compression of the elastic absorbent element.

The curves of the figure 5 correspond to successive shocks in the conditions defined above, in preamble, respectively for the first shock (C ₁ ), the tenth of 10 consecutive shocks (C ₁₀ ), and for a hundredth shock (C ₁₀₀ ). It is found that these different curves are substantially superimposed, which confirms the good elasticity of the shock absorption means, and the absence of deterioration, even after 100 shocks.

By way of comparison, for a kart made according to the technique illustrated in the patent document EP 1 805 063 a force of 20,000 Newton causes a decline of about 11 cm at the first shock, and more than 14 cm at the hundredth shock, for a total energy absorbed less.

It will also be noted that the guide element, whatever its embodiment, may be disposed in a radially offset position relative to the axis of the associated column 23. For example, the guide elements 25 may remain arranged in the horizontal plane of the frame 1 corresponding to the plane of the Figures 1 and 2 but by being deported laterally, or they may still be arranged in a lower or higher plane. In such cases, the body 26 thus deported radially will be used, by means of lateral or other tabs, remote support for a sheath or sleeve surrounding the column 23, the tabs thus ensuring compensating inverse offset. It is thus easy to overcome the need for passage 4.

Claims (12)

1. Go-kart comprising a chassis (1, 2), a protection element (12, 13) which is fitted on the front of the chassis (1, 2) and means (11, 22, 23, 24, 25, 26)for absorption of the kinetic energy induced by an impact on the protection element (12, 13), characterised in that the absorption means (11) comprise:

   - at least one resilient absorbing element (23) which is fitted between the chassis (1, 2) and the protection element (12, 13), and can go from a state of rest to a compressed state, and conversely; and

   - at least one buckling control element (25) which is designed to oppose buckling deformations of the resilient absorbing element (23) when the latter is not in the state of rest, and is fitted such as to be mobile in pivoting relative to the chassis (1, 2) around a predetermined angular range of approximately 15 degrees or even 30 degrees on both sides of the direction of the longitudinal axis (10) of the said go-kart.
2. Go-kart according to claim 1, characterised in that the at least one buckling control element (25) acts on the at least one corresponding resilient absorbing element (23), such as to permit in succession, during an impact:

   - a phase of compression of the said resilient absorbing element (23);

   - a phase of compression with controlled buckling, wherein the buckling control element (25) restrains the resilient absorbing element (23) such as to oppose its buckling.
3. Go-kart according to either of claims 1 and 2, characterised in that the at least one buckling control element (25) is provided with an anti-dislocation device (27).
4. Go-kart according to any one of claims 1 to 3, characterised in that the at least one buckling control element (25) is fitted on the chassis (1, 2) such as to be able to pivot in a predetermined angular range against the angular return force of resilient means (22, 23), towards an orientation of state of rest.
5. Go-kart according to any one of claims 1 to 4, characterised in that the at least one buckling control element (25) co-operates with at least one resilient connection (22) and/or a ball joint.
6. Go-kart according to any one of claims 1 to 5, characterised in that the at least one resilient absorbing element (23) is hollow, and in that the buckling control element (25) extends in the interior of the said resilient absorbing element (23).
7. Go-kart according to any one of claims 1 to 6, characterised in that the at least one resilient absorbing element (23) and/or at least one buckling control element (25) is/are cylindrical.
8. Go-kart according to any one of claims 1 to 7, characterised in that the absorption means (11, 22, 23, 24, 25, 26) comprise at least two resilient absorbing elements (23) which extend parallel to a longitudinal axis (10) of the chassis (1, 2).
9. Go-kart according to any one of claims 1 to 8, characterised in that the chassis (1, 2) bears a first plate (3) which is designed to co-operate with a second plate (13) associated with the protection element (12), the at least one resilient absorbing element (23) being fitted between the first and second plates (3, 13).
10. Go-kart according to claim 9, characterised in that the first and second plates (3, 13) comprise end sections (31, 32; 131, 132) which are coupled to one another by a sliding connection, an embedded connection or a guided connection.
11. Device (11) for absorption of kinetic energy between two parts of a go-kart, characterised in that it comprises:

    - at least one resilient absorbing element (23) which is designed to be fitted between a chassis (1, 2) and a protection element (12, 13), and can go from a state of rest to a compressed state, and conversely; and

    - at least one buckling control element (25) which is designed to oppose buckling deformations of the resilient absorbing element (23) when the latter is not in the state of rest, and is fitted such as to be mobile in pivoting relative to the chassis (1, 2) of the said go-kart around a predetermined angular range of approximately 15 degrees or even 30 degrees on both sides of the direction of the longitudinal axis (10) of the said go-kart.
12. Energy absorption device according to claim 11, characterised in that the at least one resilient absorbing element (23) is hollow, and in that the at least one buckling control element (25) extends in the interior of the said resilient absorbing element (23).

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